Sewing mechanism for sewing machines



April 2, 1935.

A. QHITI SEWING MECHANISM FOR SEWING MACHINES Filed Dec. 2, 1952 2 Sheets-Sheet 1 I llllllllllJ April 2, 1935. A; CHITI 1,996,324

SEWING MECHANISM FOR SEWING MACHINES Filed Dec. 2, 1932 2 Sheets-Sheet 2 Patented Apr. 2, 1935 UNITED STATES SEWING MECHANISM FOR. SEWING MACHINES Aroldo Chiti, Turin, Italy Application December 2, 1932, Serial No. 645,471 In Italy December 10, 1931 7 Claims.

In sewing machines which do not employ a shuttle with rectilinear motion, i. e. in sewing machines of the type employing a rotary hook or of other types derived therefrom, the said hook is provided with a'beak for catching thethread given off by the needle and for looping it about a second stationary member which is the bobbin case, in order to 'form the lock stitch. It is already known that the loop formed by the thread must be opened sufficiently to allow the bobbin case to be passed through it. In order to effect the pening of the loop, the base of the hook beak must be made sufficiently large so that the loop becomes large enough to allow the passage of the bobbin case through it. For this purpose the thread of the loop runs up from the point to the base of the hook beak along the inclined plane formed by one side of the hook beak. In order that this inclined plane shall not resist excessively the running of the thread and thus wear or break it, a very slight inclination is given to the hook beak side, that is, the hook beak must be made long.-

Considering that to free completely the loop of the thread from the bobbin case it is necessary to effect an angular displacement of the hook through 180 with respect to the bobbin case, plus the length of ,the hook beak, it is easily understood that'the longer the beak. of the hook the greater must be this angular displacement. But as the angular displacement increases, the giving oil the thread is retarded, while it is best to anticipate it as much as possible in order to make this phase last longer to avoid violent pull of the thread against the hook when the machine is speeded up. This invention relates to a type of hook and bobbin case, by which it is possible to reduce considerably the usual length of the beak, more particularly to reduce it by an extent corresponding to the idle stroke of the hook. The feeding of the thread is considerably facilitated and the efliciency of the machine, with the same speed of rotation, is increased. This is obtained chiefly by causing, through the special shape of the hook and of the bobbin case, the thread loop to bridge between two opposite beaks of the rotary hook and bobbin case, respectively,,which are relatively moved towards each other. The thread is caught by its loop between the two beaks and is carried along by the rotary hook beak and wound about the bobbin case, which gives oif the necessary thread length by virtue of its particular shape. Heretofore, the loop was opened by virtue of the tapered form of the beak, while according to this invention the rotary hook beak merely serves the purpose of catching andconveying the loop which is opened as'it is given off. Therefore a beak of reduced length will be sufficient, as the bobbin-case cooperates with it for passing 5 the bobbin case through the thread loop. The device which will be described with reference to the accompanying drawings can be employed in connection with existing machines, which shall be modified accordingly'in the hook and bobbin l0 case, or it can be adopted in the manufacture of special machines which will utilize its particular properties. As will be seen from the examples described hereinafter, the device provides for an axial engagement betweenthe hook and the bobl5 bin case, one of said members being provided with a groove and the other with a cylindrical ridge fitting within the former. This ensures a" perfect centering of the two members during the working and considerably improves the working 20 of the machine of which the use' and upkeep are made easier. I

The accompanying drawings show some manners of carrying out the object of this invention.

Figures 1, 2 and 3 show the rotary hook and bobbin case of a rotary hook machine about to catch the loop, in front view, plan view and axial cross section, respectively.

Figure 4 shows a detail on an enlarged scale.

Figures 5 and 6 show the rotary hook according to Figures 1 and 2 in its forward position after catching the loop in front and side view, respectively.

Figures 7 and 8 show the bobbin case according to the preceding figures in side and front view, respectively.

Figures 9 and 10 are a plan view partly in axial cross section, and a rear view, respectively, of the rotary hook according. to the preceding figures adapted for use in a double rotary hook machine.

Figure 11 is a partially sectional plan view showing the rotary hook according to the preceding figures in connection with an oscillating rotary hook machine.

Figures 12, 13, 14, 15 show a hook for rotary hook machines of the usual construction, modified according to this invention, in plan, cross sectional, front and rear view, respectively.

Figures l6, l7 and 18 show the hook of a central bobbin machine modified according to this invention in front, plan section. i

In Figures 1 to 3, the hook I is in the form of a ring and is supported by the hub 2 which is adapted to be keyed on the driving shaft, the

view and in axial cross .between the two hooks.

hub being provided with a flange 2a on which the hook I is mounted by its edge like a cover by means of a bayonet joint 3. The hook I has a flat face and an annular circular groove la is forms-d in the thickness of the hook on its inner side. The hook I is formed with an inner beak 4 having an inclined surface which joins the base of the beak with the outer side of said groove. In Figs. 1 and 2 it will be seen that the beak is considerably reduced in length with respect to the known constructions.

The bobbin case 5 (Figures 7 and 8) is made with conical faces and with an annular ridge So on its periphery which engages with light friction the groove In on the hook I. The bobbin case is held between the flange 2a and the hook and is provided with the usual tooth 8 servin to prevent rotation of the bobbin case. The thread bobbin R is lodged within the bobbin case in any suitable manner. The ridge 5a is formed with a beak 8, of which-the form is clearly shown in Figures '7 and 8,- which is directed opposite from the beak 4 of the hook I (Figure 1), so that when an end of the loop 0 bridges on the groove In of the book by virtue of the rotary motion of this latter, the two'beaks 4 and 8 are situated on axial planes which at flrst coincide and then diverge from each other. The loop is thus driven by the beak l and opened, even if the beak is short and flatand the hook face on which one end of the loop moves is not tapered as in previous machines (Fig. 2). This is made possible by the fact that the beak 8 of the bobbin case assists in holding and opening the loop.

Figures 5 and 6 clearly indicate the working of the device. The-loop c is given off by the needle a, is caught by the beak l and brought towards the beak 8 which catches it in turn holding the end b; the beak 4, upon further rotation of the hook I, pulls the end d which slides on the flat face of the hook passing in front of the bobbin case 5, while the portion 1 between the ends b and d passes behind the bobbin case.

Figure 4 shows a yielding means between the flange 2a and the bobbin case 5. The flange 2a carries a. supporting surface I!) for the bobbin case, which is a circular sector of a width exceeding three-fourths of a circumference, by means of small springs 20. Should thread waste enter between the hook and bobbin case, these latter do not jam and the working of the machine is not injuriously affected. A simple cleaning operation will restore the mechanism to its normal working conditions. 7

Figures 9 and 10 show the device employed in connection with double hook machines and the practical usefulness of this construction will be clearly seen from the drawings. Two hooks I are placed opposite. each other, their axes being in alignment, and the two needles a are situated The flanges 2a are connected to the hubs 2 by means of an arm 2b thereby providing space between the hubs and hooks I to permit the removal of the bobbins R on the side opposite to the needles. The bobbin case is held by a rod II through an arm I2, 01' which the end I2a is enlarged and reaches in the hollow 5 of the bobbin case (Figure 'I) with some clearance to permit the passage of the thread. The rod I2 is concentrical to the shaft 9 on which the hub 2 is keyed and revolves in the support II.

The two hooks are easily removed from or drawn towards each other as the shafts 9 and rods II are telescopically or otherwise axially slidable.

Figure 11 shows a hook construction for oscillating hook machines. The hook I is carried by the arm 2b of the hub 2, while the bobbin case 5 enclosing the bobbin held by the usual means, e. g. a cover R1, can be removed with the bobbin in front.

As the hook is of the oscillating type, the thread is free to pass behind the hook without being disturbed by the arm 2b.

Figures 12 and 13 show the device according to this invention employed in connection with a rotating hook machine of the usual type in elevation and sectional view.

Figures 14 and 15 show separately the hook and bobbin case from the side of the groove and ridge, respectively.

The hook I is of the usual form, is fixedly connected with the hub 2, provided with the beak 4 and formed with the annular circular groove Ia entered by the ridge 5a of the bobbin case 5. The ridge is cut away at its upper portion through which passes the axis of the needle a and where it is formed with a beak 8 performing the function of the beak 8 of the bobbin case 5 according to Figures 1 and 2, namely holding and opening the loop together with the beak of the hook I, which can therefore be made much shorter than usual, which results in the advantages in working referred to above. Moreover, the annular engagement between the hook and bobbin case keeps this latter perfectly centered and supported during working, without its weight being imposed upon the thread. The bobbin case is kept against rotation by an abutment entering the notch 6, equivalent to the usual stopping means.

The device can be employed also in connection with central bobbin sewing machines, in order to hold the hook centered with respect to its guide ring. The hook I is formed for this purpose (Figures 16, 17 and 18) with a circular groove Ia. The case 5 is provided opposite the groove Ia with a cylindrical ridge 5a. The hook is otherwise of the usual form, according to the type of the machine, but for the beak 8 of the ring which can be conveniently shaped.

The hook is thus reliably supported by the 'case and is kept centered during its rotation, the cooperation of the beak l of the hook I with the beak 8 of the case 5 assisting in opening the loop I and generally increasing the reliability of working.

The invention is not limited to the examples described and illustrated on the drawings, but can be used in a large number of manners besides those specified.

What I claim is:

1. Sewing mechanism for sewing machines comprising, in combination, .a needle adapted to form a thread loop, a hook having a circular guiding groove whose open side is turned to the side opposite to the needle, a beak on the hook, said groove extending into the beak, a bobbin case guided in said groove, andabeak on said case running along the bottom of said groove in such manner that in the relative movement of the hook and of the bobbin case the thread loom,v caught by the hook beak, forms a bridge across 2. Sewing mechanism for sewing machines comprising, in combination, a needle adapted to form a thread loop, a hook having a circular guiding groove, the open side of which is turned away i V I *ition, and rodsccarryingssaid stationary arms i said rotating shafts.

from .the needle, a beak on the hook, said groove 2 extending into said beak, said beak being just long enough to catch the loop, an inclined surface which joins the base of said beak with the outer side of said groove, a bobbin case'g uided in said groove, and a beak on said case adapted to run on the bottom of said groove, in a manner that in the relative movementof the hook and of the bobbin case the thread loop, caught by the beak on the hook, bridges across said groove and is caught by the beak of the bobbin case and caused to run up along said inclined surface so that it is opened to allow the passage of the bobbin case through the loop.

3. Sewing mechanism for sewing machines comprising, in combination, a needle adapted to form a thread loop, a hook having a circular guiding groove, the open wall of which is turned to the side opposite to that on which the needle moves, a beak on the hook, said groove extending into the beak, said beak having a length just suflicient to catch the loop, an inclined plane which joins the base of said beak with the outer side of said groove, a bobbin case, a circular concentric partly cut-away ridge on said case adapted to engage in said groove, and a beak at one end of said ridge so that in the relative movement of the hook and of the case the thread loop, caught by the beak of the hook, bridges across said groove and is caught by the beak of the case and caused to run up along said inclined surface so that it is opened to allow the passage of the case through the loop.

4. Sewing mechanism for sewing machines comprising, in combination,'a pair of needles each adapted to form a thread loop, a pair of hooks, each having a circular guiding groove, the open side of which is turned to the opposite side to that in which the needles move, abeak on each hook, the groove extending into the beak, said beak having a length just sufllcient to catch the loop,

an inclined surface which joins the base of each of said beaks with the outer side of the corresponding groove, a pair of bobbin cases, a circuthe passage of the cases through the corresponding loops, arms for supporting said hooks, hollow rotating shafts carrying said arms, said :arms being-in alignment with each other, stationary arms for holding said bobbin cases against rota- 5. Sewing mechanism for sewing machines comprisingfin combination, a needle adapted to .form a thread loop, a Ehcok having a circular guiding groove, theiopencend of which is turned .to the side opposite'i-to' that in which the needle moves, a beak onitheihook, the groove extending into said 'beak, -:'a fbobbin case guided in said groove, and a beak on said case adapted to run on the bottom of said groove in such manner that in the relative movement of the hook and of the case the thread loopncaught by the beak of the hook, bridges 8OI'OSS'F-SEIHYEIOOVG and is caught by the beak of the case and caused to run up along the beak of the hook-so-that it is opened to allow the passage of the casetthrough the loop, a rotating flanged shaft-andatbayonet joint for attaching said hook to'thetflange of the shaft.

6. Sewing mechanism for sewing machines comprising, in combination, a needle adapted toform a thread loop, ahook having a circular guiding groove, thec'open side of which is turned away frcm'the-sidelin'which the needle moves, a

caused to run up alongthe beak of the hook so that it is opened to allow the passage of the case through the loop.

'7. Sewing mechanism for sewing machines comprising in combination, a needle adapted to form a thread loop, a hook having a circular caught by the beak of the hook, bridges on said groove and is caught by the hook of the case and guiding groove,,the open side of which is turned a to the side opposite the needle, a beak on the hook, said groove extending into the beak, said beak having a length just suflicient to catch the loop, an inclined surface which joins the base of said beak with the outer. side of said groove, a bobbin case guided in saidrgroove, and a beak on said case which runs'onithe bottom of said groove, in a manner that .in'ithe relative movement of the hook and of the case the thread loop, caught by the beak of the h'ook, bridges on said groove and is taken by theih'ookloi' the case and caused to run up on saidiinclined plane so that it is opened toallow-the passage of the case through the loop, an arm for supporting said hook, and a rotating shaft on which is keyed said arm in order to leave a free space betweenisaid hook and said shaft for themovementtoftheneedle.

' fAROLDO CHITI. 

